Embodiments of the invention relate generally to integrated circuit (IC) packaging and, more particularly, to a method and apparatus for package fabrication that reduces chip and package failure due to outgassing.
A variety of approaches have been developed for fabricating IC packages (i.e., chips). One such approach is a embedded chip build-up (ECBU) packaging approach, in which a window frame structure is positioned about an IC element and coupled to one or more polymer films, with the one or more polymer films subsequently being electrically connected to the IC element and window frame structure by way of vias and metal interconnects. The window frame structure is mechanically rigid in nature and acts to control package flatness and stresses.
Existing window frame structures used in a ECBU packaging process can, however, lead to several challenges during fabrication. That is, moisture and other gasses may be released during build-up fabrication that can be trapped in the package. The moisture and other gasses can have a negative impact on the final product (i.e., the electronic package). For example, moisture can cause corrosion on package interconnects, thus effecting the reliability of the electronic package. Further, other gasses that are outgassed can fall and condense onto a dielectric layer of a package during fabrication potentially degrading the integrity of the package.
As fabrication continues, this moisture, along with other materials that may be outgassed, may then become trapped between dielectric and other layers of an electronic package. During fabrication, testing, or use, such trapped moisture or outgassed material can cause these layers to delaminate from the surface to which they are adhered. For example, when modules are exposed to high moisture and then exposed to solder reflow temperatures such as two hundred and twenty degrees Celsius for eutectic Sn:PB or two hundred and sixty for lead-free solders, trapped moisture can turn gaseous, apply pressure within a build-up interconnect structure, and create a de-lamination site that may lead to module failure. With smaller modules (e.g., modules that are ten to twenty millimeters square or less), the maximum distance moisture generally needs to travel to escape is often only a few millimeters, such as two to five millimeters. However, as a package (i.e., a module) grows to forty to sixty millimeters square, the maximum travel distance of moisture can increase to fifteen to twenty millimeters or more. Accordingly, the area on a chip that may trap moisture also increases as the package size increases. The longer paths and their increased areas of trapping can greatly increase the forces that cause de-lamination.
As such, it may be desirable to have a system that has aspects and features that differ from those that are currently available and that solves at least the aforementioned problems. Further, it may be desirable to have a method that differs from those methods that are currently available.